At-Tawba 9:10

(They have purchased with the Ayat of Allah a little gain,) idolators exchanged following the Ayat of Allah with the lower affairs of life that they indulged in,

(and they hindered men from His way), trying to prevent the believers from following the truth,

(evil indeed is that which they used to do. With regard to a believer, they respect not the ties, either of kinship or of covenant!) 9:9-10. We explained these meanings before, as well as, the meaning of,

(But if they repent, perform the Salah...)

وَأَقَامُوا الصَّلَاةَ وَآتَوُا الزَّكَاةَ فَإِخْوَانُكُمْ فِي الدِّينِ (Then, if they repent and establish salah and pay zakah, they are your brothers in faith).

Here we are being told that once an enemy - no matter how deadly and no matter how hurtful he has been - becomes a Muslim, things change dramatically. Allah Ta` ala forgives his past sins, all of them. So, it becomes obligatory on Muslims too that they should forget the past, start afresh, take them as their brothers in faith and do whatever it takes to fulfill the rights enjoined under such relationship.

Three Conditions of Entry into the Islamic Brotherhood

This verse makes it clear that there are three conditions of entry into the Islamic brotherhood: (1) Taubah or repentance from Kufr and Shirk, (2) establishment of Salah and (3) payment of Zakah - because, 'Iman (faith) and Taubah (repentance) are concealed matters. Common Muslims cannot find out their reality. Therefore, two of their outward signs were mentioned, that is, Salah and Zakah.

Sayyidna ` Abdullah ibn ` Abbas ؓ said: ` This verse has made the blood of Muslims, who qualify as ` the people of Qiblah,' unlawful حرام (haram).' In other words, people who establish Sarah, pay Zak-ah and have said or done nothing against Islam as proved against them, shall be taken as Muslims in the matter of all religious injunctions - even though, they may not have true 'Iman (faith) in their hearts, or have hypocrisy نفاق (nifaq).

This is the verse Sayyidna Abu Bakr ؓ had quoted in support of his declaration of Jihad against those who had refused to pay Zakah after the passing away of the Holy Prophet ﷺ . The noble Companions ؓ before whom he had made this assertion were satisfied with his approach. (Ibn Kathir)